1. Field of the Invention
The present invention relates generally to harvesting equipment and, more specifically, to a fan for the air system of a harvester such as a cotton picker or stripper.
2. Related Art
Machines such as cotton pickers and strippers typically have a fan for moving harvested crop from the row units to the basket. The fan includes a housing carried by a frame-mounted support. A rotor supported within the housing draws air into a central inlet and expels air through a tangential outlet to a series of ducts leading to the row unit areas. Some fans include pair of donut-shaped inserts located on opposite sides of the rotor to act as seals between the low and high pressure areas. The efficiency and output of the fan is heavily dependent upon the placement of the inserts relative to the sides of the rotor. If the inserts touch the rotor, drag decreases the fan efficiency. However, if too large of a gap exists between rotor and insert, the fan output pressure will drop significantly as high pressure air leaks back to the low pressure inlet. The gap between the rotor and inserts is adjusted (as discussed below with reference to FIG. 1) using washers or shims at a series of mounting bolts which are spaced equidistantly around each insert. Indented areas on the rotor side of the insert adapted to receive the mounting bolts decrease the ability of the insert to seal between high and low pressure areas. Shimming requires removal of the fan from the harvester, as well as installation and/or removal of washers at each bolt location. As a result, proper adjustment of the fan is time-consuming and inconvenient. The shims or washers provide relatively imprecise adjustment so that fan output and efficiency cannot be fully optimized. In some instances, an improperly adjusted fan gap has been found to adversely affect fan performance so much that minimum fan specifications cannot be met